Until now, the consensus about Tyrannosaurus rex is that it could run at similar speeds to today's Olympians. A new study shows that the Cretaceous carnivore's bones would have buckled under the strain.
In one of the most memorable chase scenes in modern movie history, visitors to Jurassic Park - in a jeep careering at full throttle - are seen desperately try to outpace a rapidly advancing Tyrannosaurus rex.
For a long time, there's been debate about how fast the "king of dinosaurs" was capable of sprinting to hunt down its quarry. The consensus was that - with its long limbs - the T. rex was capable of reaching similar speeds to modern-day sprinters.
However, new research shows that that, in fact, the most fearsome of creatures would have had to move far more slowly.
Scientists at the University of Manchester in the UK say that, at high speed, the dinosaur's bones would simply have buckled.
In a paper published by the journal PeerJ, , the researchers examined the gait and biomechanics of the T. rex, using high performance computing to test a new simulation model.
The simulation, which factored in machine learning with what paleontologists know about the strength of T. rex bones, tendons and ligaments, showed that running at any speed would have broken the dinosaur's bones.
T. rex's speediness debated for decades
While it had been thought the T. rex might run up to 45 kilometers per hour (almost 30 miles per hour), the new simulation showed it would have been limited to far less than half that, about 18 kmh.
Fleet-footed humans could easily outpace a T. rex, with Jamaican sprinter Olympian Usain Bolt's personal best standing at 44.4 kmh.
"The running ability of T. rex and other similarly giant dinosaurs has been intensely debated amongst palaeontologist for decades," said Professor William Sellers. "However, different studies using differing methodologies have produced a very wide range of top speed estimates.
"Here we present a new approach that combines two separate biomechanical techniques to demonstrate that true running gaits would probably lead to unacceptably high skeletal loads in T. rex.'
Ambush or scavenge?
It's all led to a rethink about how the dinosaur might have survived.
"It certainly would not have been able to chase down faster-moving prey animals," Sellers told the Reuters news agency. "That leaves other hunting options such as ambush, and of course it means that ideas such as 'T. rex the scavenger' have to be reconsidered."
Scientific theories about dinosaurs in general - and the T. rex in particular - are in constant contention. A study by Australia's University of New England in June said it had "without question" disproved recent evidence that the T. rex had feathers, reviving the more conventional theory that the animal had scales.